Method of crystallizing organic oligomer, epoxy resin composition containing organic oligomer obtained by the method and epoxy resin cured material

ABSTRACT

For the purpose to provide a method to crystallize organic oligomer of low crystallizing speed without using a specific apparatus and without wasting huge energy, and to provide epoxy resin composition suited as the sealing material for semi-conductor containing the organic oligomer obtained by said method following method is found out. That is, the method for crystallization of organic oligomers comprising, after fluidizing powdered or granulated seed crystals of organic oligomer in an apparatus with powder stirring mechanism, pouring liquid of same crystallizable organic oligomer continuously or by batch into said apparatus so that to mix and disperse, then growing up crystals of the organic oligomer in said apparatus.

FIELD OF THE INVENTION

The present invention relates to the method for preparation of a novelmethod for crystallization of organic oligomer in the field of chemicalindustry, food industry and petroleum industry, especially relates toprovide the method for preparation of a new method for crystallizationof crystallizable epoxy resin oligomer.

DESCRIPTION OF THE PRIOR ART

In various industries, a unit operation of crystallization is appliedwidely. Typically, said unit operation can be divided to two types, thatis, one is crystallization from poor solvent and another one iscrystallization from molten state. However, the crystallization frompoor solvent needs many processes such as separation of crystal frommother liquor, drying process of crystal or recovering process ofsolvent from mother liquor, and can not be said as a profitable method.While, the crystallization from molten state has a limitation from theview point of equipment, and specifically, the methods to extrude asstrands by an extruder, to cool on a belt flaker, to knead and cool in akneader or to cool in a flat container are known. However, in the casewhen melt viscosity of organic oligomer is low and physical intensity atmolten state is insufficient, the extruder can not be used. Further, inthe case of the belt flaker, it is necessary to complete thecrystallization in several minutes (about 2-5 minutes) and to solidifyso as to be removed from the belt. Otherwise, the method to cool andcrystallize in separated container can be mentioned.

As mentioned above, in the case which can use a kneader or a beltflaker, industrially continuous production is possible, on the contrary,in the case of crystallization by cooling in a separated container, ittakes long time to the crystallization. During the process, the space tostore the container is necessary, the operation to remove the productfrom the container and the shape of product removed from the containeris coarse and has sharp angle and is dangerous for handling. Further, itis necessary to make the size of crystal finer, and has a possibility tocontaminate foreign substances during the granulating process, and isnot suited as the effective industrial production.

Regarding the crystallization of epoxy resin as the crystalline organicoligomer, in the Patent Document 1, the processing by moldingcharacterized crystallizing and soldificating said resin by addingcrystalline nucleus (curing agent or filling agent) to liquid epoxyresin in supercooling state at room temperature is disclosed. Since thismethod is characterized to add foreign substances as crystallinenucleus, this method can not be applied to the case which handles puresubstance.

In the Patent Document 2, the following method for crystallization isdisclosed. That is, to the epoxy resin of diglycidylether of3,3′,5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane in the state ofmolten liquid, fine particles of said epoxy resin crystal are added andcrystallized by stirred under the state maintaining liquid state at thetemperature lower at least 20° C. than a melting point of the epoxyresin. By adding seed crystals, the time for crystallization can beshortened, however, by this method, an extruder or a belt flaker can notbe used and is necessary to be cooled and crystallized in a separatedcontainer, and the realization of industrial production is difficult.

In the Patent Document 3, the method for preparation of granular productof epoxy resin comprising, growing crystalline nucleus maintaining thecrystallizable epoxy resin which is in supercooling or molten state atthe temperature between 40° C. or mores and lower than melting pointthen granulating, is disclosed. However, although this method is themethod to form strands by a twin screw extruder and to granulate by apelletizer, it is not possible to form strands in the case when thecrystallizable epoxy resin of lower viscosity is used, further the timenecessary for the crystallization is very long. In the Patent Document4, the crystalline solid epoxy resin is obtained by cooling the moltenstate resin of diglycidylether of 2,7-naphtalenediol to the temperaturelower than 30° C. in a kneader so as to crystallize and by shearing it.However, since this method requires very huge stirring power, and ischaracterized as a batch production, this method is an ineffectivemethod and is not suited for the industrial production.

In the Patent Document 5, the following method is disclosed. That is,after mixed and solubilized the crystallizable epoxy resin and the noncrystallizable epoxy resin at the temperature more than the meltingpoint of the former and cooling down by the cooling speed lower than 5°C./min, under stirring speed of lower than stirring Reinold's number 20.However, this method can not be applied to the case of crystallizableepoxy resin whose crystallization speed is slow.

As mentioned above, in the conventional arts, the crystallization methodsuited for the industrial scale production of organic oligomers whosecrystallization speed is slow and whose viscosity is low is not proposedyet.

-   Patent Document 1: JP Patent Laid-Open Publication 6-198644-   Patent Document 2: JP Patent Laid-Open Publication 7-179564-   Patent Document 3: JP Patent Laid-Open Publication 9-324029-   Patent Document 4: JP Patent Laid-Open Publication 2000-119369-   Patent Document 5: JP Patent Laid-Open Publication 2001-114983

DISCLOSURE OF THE INVENTION

The inventors of the present invention have investigated variously aboutthe method for crystallization suited for the industrial scaleproduction of organic oligomers whose crystallization speed is slow andwhose viscosity is low and accomplished the present invention. Theobject of the present invention is to provide a method forcrystallization which promises an effectivity and profitability for theindustrial production even if the crystallizable organic oligomer whosecrystallizing speed is slow and which can not form strand because of lowmelt viscosity.

The important point of the present invention is a method forcrystallization of organic oligomers comprising, after fluidizingpowdered or granulated seed crystals of an organic oligomer in anapparatus with powder stirring mechanism, pouring liquid of samecrystallizable organic oligomer continuously or by batch into saidapparatus so that to mix and disperse, then growing up crystals of theorganic oligomer in said apparatus.

That is, in the present invention, previously crystallized organicoligomer is crushed to powder or granule and use said crushed powder orgranule of the organic oligomer as the seed crystals, and fluidizingsaid seed crystals by stirring in an apparatus with powder stirringmechanism. In this state, same crystallizable organic oligomer of liquidstate is poured into said apparatus by continuous operation or by batchoperation so that mix and to disperse and to grow up crystals in saidapparatus.

And according to one embodiment of this method, it is desirable that thecrystallization temperature is lower at least 10° C. than the meltingpoint of said organic oligomer and is within the temperature range offrom 200° C. to 0° C. Further, it is desirable to remove the heat ofcrystallization by a cooler attached to the apparatus with powderstirring mechanism or to introduce previously cooled inert gas into theapparatus with powder stirring mechanism so as to exchange the heat bycontacting with organic oligomer particles in said apparatus.

Further, in the present invention, it is desirable to produce organicoligomer crystals continuously by picking out a part of or whole organicoligomer crystals from the apparatus with powder stirring mechanism, andprovide powdered or granulated organic oligomer crystals againcontinuously or by batch operation to the apparatus with powder stirringmechanism, desirably passing through a pulverizer, as seed crystals.

In the present invention, it is further desirable that the organicoligomer is crystallizable resin low moleculer polymer, and inparticular, it is furthermore desirable that the crystallizable resinlow moleculer polymer is crystallizable epoxy resin low molecular weightpolymer. And, desirably the crystallized ratio of the organic oligomercrystal is 65% or more.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the flow of the process of continuous crystallization oforganic oligomers, and 1 is an apparatus with powder stirring mechanism,2 is a pulverizer, 3 is an inlet route, 4 is an outlet route, 5 is acirculation route, F is a molten oligomer feed line and M is a screw.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be illustrated more in detail according tothe following description.

The term of crystallizable organic oligomer indicates a crystallizableresinous state low molecular weight polymer whose molecular weight isfrom 200 to 2000. As the examples of said crystallizable organicoligomer, aromatic polycarbonate, aromatic polyester, poly lactic acidresins or aromatic epoxy resin can be mentioned, however, not intendingto be limited to them, and any organic oligomer with crystallinity canbe applied.

Further, at the pouring of liquid state crystallizable organic oligomer,both molten state liquid of the temperature higher than melting pointand supercooled liquid of the temperature lower than melting point canbe used, however, the temperature is desirably within the range of 30°C. higher than the melting point and 20° C. lower than the meltingpoint, because the efficiency for the generation of crystals is high.When the temperature is more than 30° C. higher than the melting point,the cooling efficiency in the apparatus with powder stirring mechanismbecomes low, while, the temperature is more than 30° C. lower than themelting point, the efficiency of generation of crystals becomes low.

As the apparatus with powder stirring mechanism of the presentinvention, any type of a powder mixing tank with a stirring impeller ora fluidized bed mixing tank which can introduce fluid gas from bottomcan be used. As the powder mixing tank with a stirring impeller, ahorizontal mixer with ribbon shape stirring propeller, a vertical V typemixer (Nauter type, Helical ribbon type) can be mentioned, inparticular, a type which inner screw rotates and revolves can bedesirably used. Further, for the purpose to remove the heat ofcrystallization, it is desirable to install a heat transferring device,such as jacket. It is possible to pass coolant such as water in thejacket, however, in the case that the heat transferring area is toosmall, it is possible to blow cooled nitrogen gas, cooled carbon dioxidegas or cooled air directly to the mixer and to cool the contents. As thepulverizer, batch type crushing method or continuous crushing method canbe used. As the specific example of the crushing machine, jaw crusher,gyratory crusher, hummer crusher, roll crusher, ball mill, edge-runner,hummer mill, pin mill, cutter mill, feather mill, vibration rod mill,cascade mill, turbo mill, pot mill, compound mill, radial mill, towermill, circular vibration mill, disk mill, high swing ball mill,centrifuge ball mill, atomizer, pulverizer, super micron mill, jet millor colloid mill can be mentioned.

The important point in the method for crystallization of the presentinvention is to drop crystallizable organic oligomer of liquid stateinto seed crystals which is powdered or granulated organic oligomer andto adhere the seed crystals on the surface of liquid drop and todisperse the liquid drop to the surface of which seed crystals areadhered into powdered or granulated organic oligomer. Further, at thepicking out the organic oligomer crystals continuously as the product,it is desirable that a part of it is provided again continuously or bybatch operation to the apparatus with powder stirring mechanism as seedcrystal and carry out the crystallization of crystallizable organicoligomer continuously by adjusting the amount of liquid crystallizableorganic oligomer to be supplied, the residence amount in the apparatuswith powder stirring mechanism and temperature. At the stirring andcooling process in the powder mixer, the crystallization of said liquiddrop is proceeded rapidly by many seed crystals, by impact and shearingcaused by stirring and friction, and new particles (crystals) aregenerated by friction between particles. In the case when the generationof organic oligomer crystals is small, it can be improved by picking outa part of product from said apparatus with powder stirring mechanism andput back it to the apparatus after crushed. The term of powdered orgranulated (hereinafter shortened to fine particles) means to contain atleast 10%, desirably 20% more desirably 30% of 100 mesh passedparticles. In the present invention, it is desirable to make the size ofliquid drop which is provided to the stirring mixer smaller, or to dropfrom porous substance so as to disperse smoothly in fine particlesdesirable. In the present invention, when the numbers of fine particlesoligomer to be seed crystals become lacking, the size of particles inthe stirring mixer becomes larger gradually. Although the size ofparticle in the stirring mixer depends on the specie of organicoligomer, generally forms random shape particles of approximately 1 mmto 50 mm, and since a part of particles are crushed by collision ofparticles themselves, the shape of particles is apparently round withoutsharp edges. Therefore, the picking out operation and handling operationof the product becomes easy.

The present invention can be applied not only to the oligomer whosecrystallization speed is fast, but also to the oligomer whosecrystallization speed is slow. In the present invention, the desirableembodiment is to pick out the corresponding amount to the providedamount to the apparatus with powder stirring mechanism as the productcontinuously or by batch operation. Further, the most suitable residence(crystallization) time of various crystallizable organic oligomers canbe decided by adjusting the residing amount in the apparatus with powderstirring mechanism, for example, by adjusting the variation of theresiding amount in the apparatus with powder stirring mechanism,supplying amount of liquid organic oligomer and the amount the pickingout amount of the crystal product. In the present invention, the longcrystallization (residing) time is not required, however, the desirablecrystallization time is from 5 minutes to 10 hours, more desirably isfrom 10 minutes to 5 hours and furthermore desirably is from 30 minutesto 3 hours.

The desirable temperature at the crystallizing is the temperature whichis 10° C. or more under (lower) than the melting point of said organicoligomer (melting peak temperature of differential scanning calorimeter(DSC) curve), more desirable temperature at the crystallizing is thetemperature 20° C. or more under than the melting point of said organicoligomer. By too lower temperature, the surface of fused liquidsolidified by amorphous state (non-crystalline state) and does notadhere seed crystals. The desirable crystallization temperature is from200° C. to 0° C., more desirably is from 160° C. to 10° C., furthermoredesirably from 140° C. to 10° C.

As the crystallizable epoxy resin oligomer which can be used in thepresent invention, any epoxy resin with crystallinity can be used andnot limited by the chemical structure, and following compounds can bementioned as the example.

Diglycidylether compound of 3,3′,5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane,

diglycidylether compound of 3,3′-dimethyl-4,4′-dihydroxydiphenylmethane,

diglycidylether compound of 2,2′-3,3′-5,5′-hexamethyl-4,4′-dihydroxydiphenylmethane,

diglycidylether compound of 1,4-bis(4-hydroxycumyl)benzene,

diglycidylether compound of2,2′-dimethyl-5,5′-ditertiarybutyl-4,4′-dihydroxydiphenylmethane,

diglycidylether compound of 1,4-bis (3,5dimethyl-4-hydroxycumyl)benzene,

diglycidylether compound of 4,4′-dihydroxydiphenylether,

diglycidylether compound of 4,4′-dihydroxy diphenylsulfide,

diglycidylether compound of2,2′-dimethyl-5,5′-ditertiarybutyl-4,4′-dihydroxydiphenylsulfide,

diglycidylether compound of 2,5-ditertiarybutylhydroquinone,

diglycidylether compound of 4,4′-dihydroxy biphenyl,

diglycidylether compound of 3,3′,5-5′-tetramethyl-biphenol,

polyglycidylether compound of biphenylalalkylphenol,

polyglycidylether compound of phenolalalkylnapthol,

diglycidylether of tetrabrombisphenol A,

epoxy compound with mesogen structure or

stilben epoxy resins can be mentioned.

The crystallization ratio of the organic oligomers immediately after thecrystallization obtained by the method for crystallization of thepresent invention is desirably to be 65% or more, more desirably to be75-95%. When the crystallization ratio is smaller than 65%, the problemof blocking can be generated and is inferior in preserving stability andis inferior of the function as seed crystals. On the contrary, when thecrystallization ratio exceeds 95%, the crystallization (preservation)time becomes long and is not advantageous from the productiveefficiency. The crystallization ratio of the present invention can bemeasured from the colorimetric ratio between fusing calorie of obtainedcrystal of organic oligomers measured by DSC and the fused calorie ofstandard specimen whose purity of crystalline component (componentcontaining epoxy resin at both ends) is enhanced to more than 99% (area% measured by GPC) by re-crystallization using poor solvent to thecrystal. As the poor solvent, the compound selected from the groupconsisting of alcohols such as methanol, ketones such asmethylethylketone or methylisobutylketone, toluene or xylene can bementioned.

The crystallizable epoxy resin composition of the present invention canbe used together with other kinds of epoxy resin in the limitation notspoiling the characteristics of the crystallizable epoxy resin of thepresent invention. As the epoxy resin which can be used together with,any kinds of oligomer or polymer possessing two or more epoxy groups inone molecule can be mentioned. For example, orthocresolnovolac epoxyresin, phenolnovolac epoxy resin, dicyclopentadiene modified phenolepoxy resin, naphthol epoxy resin, triphenolmethane epoxy resin,phenolalalkyl (possessing phenylene structure or diphenylene structure)epoxy resin can be mentioned, and these resins can be used alone ortogether with.

The crystallizable epoxy resin composition of the present invention ispreferably the crystallizable epoxy resin composition for semi-conductorsealing material, and can contain said crystallizable epoxy resin, otherepoxy resin, curing agent such as phenol resin, curing acceleratingagent such as tertiary amine, imidazole or phosphine, inorganic fillercomposed of inorganic powder such as silica or alumina, coupling agentsuch as silane coupling agent, releasing agent such as carnauba wax,stearic acid or coloring agent such as carbon black.

As the phenol resin which can be used in the crystallizable epoxy resinof the present invention, any kinds of oligomer or polymer possessingtwo or more phenolic hydroxy groups in one molecule can be mentioned,specifically, phenolovolac resin, phenolalalkyl (possessing phenylenestructure or diphenylene structure) epoxy resin, naphtholalalkyl(possessing phenylene structure or diphenylene structure) resin, terpenemodified phenol resin, dicyclopentadiene modified phenol resin ornaphthol resin can be mentioned and these resins can be used alone ortogether with. Molecular weight, softening point or hydroxyl equivalentof these resins are not specifically restricted, however, phenol resinhaving relatively lower melt viscosity which is solid at roomtemperature and whose softening point is 110° C. or less is desirable.When the softening point exceeds 110° C., the viscosity of the epoxyresin composition becomes high and not desirable.

The inorganic filler which can be used in the present invention is notrestricted, and the inorganic filler which is ordinary used can be used.For example, fused and crushed silica powder, fused spherical silicapowder, crystalline silica powder, secondary flocculated silica powder,alumina, titanium white and aluminum hydroxide can be mentioned, andamong these compounds, fused spherical silica powder is preferably used.The shape of these fillers is desirably to be as much as spherical, andthe filling amount can be improved by mixing use of different particlesizes. The desirable blending amount of the inorganic filler used in thepresent invention is 70-95 wt % to molding material, and more desirableamount of it is 75-93 wt %. When the filling amount of the inorganicfiller is less than 75 wt %, moisture absorption amount increases, andwhen is used as the semi-conductor sealing material, cracks are easilygenerated in semiconductor device at the process of soldering reflowtreatment. On the contrary, when the filling amount of the inorganicfiller exceeds 95wt %, the fluidity of the molding material at themolding process deteriorates and the problems of non-filled, chip shiftor die pat shift of the semi-conductor unit becomes easily generated andis not desirable.

As the curing accelerating agent which can be used in the presentinvention, for example, amidine compounds such as 1,8-diazabicyclo(5,4,0)undecene-7, organicphosphorous compounds such as triphenylphosphine or tetraphenylphosphonium·tetraphenylborate or imidazolecompounds such as 2-methylimidazole can be mentioned, however, notintending to be limited to them. These curing accelerating agent can beused by alone or together with.

The crystallizable epoxy resin composition used in the present inventioncan contain additives, for example, flame retardant agent such asbrominated epoxy resin, antimony oxide, phosphorous compound, inorganicion exchanger such as bismuth oxide hydrate, coupling agent such asγ-glycidoxypropyltrimethoxysilane, coloring agent such as carbon blackor red iron oxide, releasing agent such as carnauba wax or polyethylenewax, low stress agent such as silicone oil or silicone rubber orantioxidant, when need is arisen. As the specific sealing method ofelectric parts such as semi-conductor unit by solidified compositioncontaining organic oligomer crystals, the molding method such astransfer mold, compression mold, injection mold can be used.

The process of continuous crystallization of the present invention willbe more specifically illustrated according to FIG. 1.

FIG. 1 shows the process flow of the continuous crystallization of thepresent invention, and the apparatus with powder stirring mechanism 1has a feed line for material supply F and a stirrer M. A crushingmachine 2 has an inlet route 3, an outlet route 4 and a circulationroute 5. In this kind of apparatus, liquid state organic oligomer issupplied to the apparatus with powder stirring mechanism 1 through F. Inthe apparatus with powder stirring mechanism 1, fluidize fine particlesof seed crystals which is previously introduced by screw M and generatenew crystals (random shape particles) by dropping liquid organicoligomer. Crystals grown to appropriate size are introduced into thecrushing machine 2 through the inlet route 3. In the crushing machine 2,the introduced crystals are crushed to crystals having the desiredparticle size (fine particles). Said fine particles are picked out fromthe outlet route 4, and all or a part of the fine particles are backedto the apparatus with powder stirring mechanism 1 through thecirculation route 5.

EXAMPLES

The crystallization method of organic oligomer of the present inventionwill be illustrated more in detail according to the Example andComparative Examples, however, not intending to be limited to them.

Melting point (temperature of main melting peak) and the ratio ofcrystallization is measured by a differential scanning calorimeter (DSC)under the condition of approximately 10 mg amount of specimen, 10°C./min temperature elevating speed and in nitrogen atmosphere of 30mL/min. The crystallization ratio is measured from the colorimetricratio (endothermic calorimetric ratio) between fusing calorie ofspecimens obtained in each Examples and the fused calorie of standardspecimen whose purity of crystalline component (component containingdiglycidyl ether which has zero degree of polymerization) is enhanced tomore than 99% (area % measured by GPC) by re-crystallization using poorsolvent to each obtained specimen. As the poor solvents used to thespecimens obtained from Examples 1-3, methanol, methylisobutylketone andmethylethylketone are respectively used. In cases of Comparative Example1 and Example 4, methanol is used.

Example 1

In a 360 L Nauter type mixer with jacket, 100 kg of fine particles of3,3′,5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane diglycidylether of73° C. melting point, which was previously crystallized sufficiently byspontaneous cooling and crushed, was contained and fluidized by screwand the inner temperature was cooled down to 10° C. by passing coolantthrough the jacket. Then 84 kg of fused said resin liquid of 88° C. wasdropped on fluidized fine particles under constant stirring by 1 hour.During the dropping process, the inner temperature of the mixer elevatedto 26-30° C. Crystals were dispersed as the random shape particleswithout sticking to the screw and the wall of mixer. The melting pointof the crystals picked out after 2 hours from the dropping was 73° C.,and new endothermic peak (2^(nd) peak) was observed at approximetely 60°C. Further, the crystallized ratio measured by DSC was 78%.

Comparative Example 1

To the fused liquid of 3,3′,5,5′-tetramethyl-4,4′-dihydroxydiphenylmethanediglycidylether of 75° C., 0.5 wt % of fine particles of3,3′,5,5′-tetramethyl-4,4′-dihydroxydiphenylmethanediglycidylether whosemelting point is 73° C., which was previously crystallized and crushed,was added and mixed, then poured into a can of 20 L capacity andcrystallized by spontaneous cooling. Contents were solidified after 24hours, and the crystallized ratio was 63% and 78% after 72 hours.

Example 2

150 g of fine particles of 3,3′,5,5′-tetramethyl-4,4′-dihydroxybiphenoldiglycidylether whose melting point is 105° C., which was previouslycrystallized and crushed, was previously contained into a cylindricalseparable flask of 500 mL capacity with Herical ribbon impeller, andsaid cylindrical flask was dipped in water bath so that the innertemperature was cooled down to 20° C. Then, 150 g of previously fused3,3′,5,5′-tetramethyl-4,4′-dihydroxybiphenoldiglycidylether at 120° C.was dropped on the fine particles under constant stirring by 1 hour.During dropping process, the inner temperature of the separable flaskelevated to 35° C., and the crystals were dispersed as random shapeparticles of 2-5mm size without sticking to the stirring impeller and tothe inner wall of the flask. The melting point of the crystals pickedout after 1 hour from the dropping was 105° C., and new endothermic peak(2^(nd) peak) was observed at approximetely 86° C. Further, thecrystallized ratio measured by DSC was 85%.

Example 3

The apparatus used in Example 2 was used. 150 g of fine particles of2,5-ditertiarybutylhydroquinonediglycidylether whose melting point is141° C., which was previously crystallized and crushed, was previouslycontained and cooled down by water bath. Then, 150 g of previously fuseddiglycidylether of 2,5-ditertiarybutylhydroquinone at 160° C. wasdropped on the fine particles under constant stirring by 1 hour. Duringdropping process, the inner temperature of the separable flask elevatedto 45° C., and the crystals were dispersed as random shape particles of2-5 mm size without sticking to the stirring impeller and to the innerwall of the flask. The melting point of the crystals picked out after 15minutes from the dropping was 141° C., and new endothermic peak (2^(nd)peak) was observed at approximetely 117° C. Further, the crystallizedratio measured by DSC was 90%.

Example 4

In a 360L Nauter type mixer with jacket, 100 kg of fine particles of3,3′,5,5′-tetramethyl-4,4′-dihydroxydiphenylmethanediglycidylether of73° C. melting point, which was crystallized sufficiently and crushed,was contained and fluidized by screw and the inner temperature wascooled down to 10° C. by passing coolant through the jacket. A part ofsaid fine particles were provided to a Nauter mixer as seed crystalsthrough a crusher and circulated continuously. Then molten liquid ofsaid resin of 88° C. was dropped on fluidized fine particles underconstant stirring, and a part of fine particles of crystals dischargedfrom the crusher is picked out continuously as the product. During saidprocess, the inner temperature of the mixer elevated to 21-25° C.Crystals in the Nauter type mixer were dispersed as random shapeparticles of 1-3 mm without sticking to the screw or the inner wall ofthe mixer. The melting point of this product is 73° C., and newendothermic peak (2^(nd) peak) was observed at approximetely 60° C.Further, the crystallized ratio measured by DSC was 73%.

Examples 5-7 and Comparative Examples 2-4

Blending ratio of compositions containing crystallizable organicoligomer is shown in Table 1. Numeric values in the Table shows theweight parts. Crystallizable organic oligomer, phenol novolac curingagent and additives shown in Table 1 were blended and previously mixed,then kneaded by a kneader at 100° C. After the products were cooled,crushed and the epoxy resin compositions of the blending ratio ofExamples 5-7 and Comparative Examples 2-4 were obtained. TABLE 1 Compar.Compar. Compar. Ex. 5 Ex. 6 Ex. 7 Ex. 2 Ex. 3 Ex. 4 kind of A B C D E FC.O.O. * amount of 124.6 124.6 120.0 124.6 124.6 120.0 C.O.O. * (1) 67.467.4 72.0 67.4 67.4 72.0 (2) 8 8 8 8 8 8 (3) 4 4 4 4 4 4 carbon 2 2 2 22 2 black calcium 2 2 2 2 2 2 stearate triphenyl 2 2 2 2 2 2 phosphinesilane 3 3 3 3 3 3 coupler fused 884 884 884 884 884 884 silica* crystallizable organic oligomer

Crystallizable organic oligomers A-F and (1)-(3) are illustrated asfollows:

Organic oligomer A: Crystallizable diglycidylether compound of3,3′,5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane obtained in Example1, whose melting point is 73° C. (epoxy equivalent is 193 g/eq).

Organic oligomer B: Crystallizable diglycidylether compound of3,3′,5-5′-tetramethyl-biphenol obtained in Example 2, whose meltingpoint is 105° C. (epoxy equivalent is 193 g/eq).

Organic oligomer C: Crystallizable 2,5-ditertiarybutylhydroquinonediglycidylether obtained in Example 3, whose melting point is 141° C.(epoxy equivalent is 175 g/eq).

Organic oligomer D: Diglycidylether of3,3′,5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane which is used asseed crystals in Example l(epoxy equivalent is 193 g/eq).

Organic oligomer E: Diglycidylether of3,3′,5,5′-tetramethyl-4,4′-dihydroxy biphenyl which is used as seedcrystals in Example 2 (epoxy equivalent is 193 g/eq).

Organic oligomer F: 2,5-ditertiarybutylhydroquinonediglycidylether whichis used as seed crystals in Example 3 (epoxy equivalent is 175 g/eq).

Phenol novolac resin (1): Product of Showa Hi-Polymer Co., Ltd.,BRG-555, softening point is 65° C., hydroxyl equivalent is 105 g/eq

Flame retardant agent (2): Product of Tohto Kasei Co., Ltd., YDB-360,brominated bisphenol A epoxy resin whose epoxy equivalent is 360 g/eq.

Flame retardant promoter (3): Antimony oxide

Examples 8-10 and Comparative Examples 5-7

Crystallizable epoxy resin compositions of Table 1 were cured and thecharacteristics are measured. Results are shown in Table 2. Measuringmethods are illustrated as follows.

1. Glass Transition Temperature

Measured by thermomechanical analysis (TMA) of the molded product whichis cured at 180° C. for 8 hours.

2. Water Absorption Ratio

Disk shape molded product of 50 mm diameter and 2 mm thickness which iscured at 180° C. for 8 hours is used as a test piece. The specimen isset in a pressure cooker tester of 121° C., 100% RH condition and weightchange after 120 hours is measured. TABLE 2 Ex. Ex. Ex. Compar. Compar.Compar. 8 9 10 Ex. 5 Ex. 6 Ex. 7 kind of A B C D E F C.O.O. * glass 128130 135 128 130 135 transition temp.(° C.) water 0.54 0.63 0.52 0.540.63 0.52 absorption ratio (%)* crystallizable organic oligomer

Obviously understood from the results of Examples 1-3, by crystallizingmethod of the present invention, not only easy crystallizable organicoligomer but also slow crystallizable organic oligomer can beeffectively crystallized in short time. Further, as clearly understoodfrom the results of Table 2, the epoxy resin composition of the presentinvention indicates similar characteristics to epoxy resin used as theseed crystals, and can be preferably used as the sealing material forsemi-conductor.

INDUSTRIAL APPLICABILITY

The present invention can be effectively used as the industrial method,which can crystallize organic oligomer of slow crystallization speed inshort time without wasting a lot of energy, and can pick outcontinuously as the easy handling random shape particles. Further, thecrystallized organic oligomer obtained by the method of the presentinvention can be preferably applied as the sealing material forsemi-conductor.

1. A method for crystallization of organic oligomers comprising, afterfluidizing powdered or granulated seed crystals of organic oligomer inan apparatus with powder stirring mechanism, pouring liquid of samecrystallizable organic oligomer continuously or by batch into saidapparatus so that to mix and disperse, then growing up crystals of theorganic oligomer in said apparatus.
 2. The method for crystallization ofclaim 1, wherein the temperature to generate crystals in said apparatusis lower at least 10° C. than from the melting point of said organicoligomer and is within the temperature range of from 200° C. to 0° C. 3.The method for crystallization of claim 1, wherein the removal of theheat of crystallization is carried out by means of a heat exchangerattached to the apparatus with powder stirring mechanism or byintroduction of previously cooled inert gas into the apparatus withpowder stirring mechanism.
 4. The method for crystallization accordingto claim 1, wherein the organic oligomer crystals is producedcontinuously by picking out a part of or whole organic oligomer crystalsfrom the apparatus with powder stirring mechanism, and providing said apart of or whole organic oligomer crystals again continuously or bybatch operation to the apparatus with powder stirring mechanism passingthrough a crushing machine.
 5. The method for crystallization accordingto claim 1, wherein the organic oligomer is crystallizable resinous lowmolecular weight polymer.
 6. The method for crystallization according toclaim 1, wherein the organic oligomer is crystallizable epoxy resinlower molecular weight polymer.
 7. The method for crystallizationaccording to claim 1, wherein the crystallized ratio of the organicoligomer crystals is 65% or more.
 8. A crystallizable epoxy resincomposition comprising, the crystallizable epoxy resin lower molecularweight polymer obtained by the method of claim 6 and an epoxy resincuring agent.
 9. A crystallizable epoxy resin composition used as thesealing material for electronic parts comprising, the crystallizableepoxy resin lower molecular weight polymer obtained by the method ofclaim 6 and an epoxy resin curing agent.
 10. A cured product obtained bycuring the epoxy resin composition of claim 8.